As an example of a conventional check valve device, a device disclosed by Patent Document 1 (JP 2005-172206 A corresponding to US 2005-0126649 A1) is known. The check valve device of Patent Document 1 obtains a sealing effect by line contact between an outer circumferential rim of an upstream side of a sealing part of a rubber valving element and a circular edge of a partition wall, and prevents a backward flow. The valving element is a component in which a valve portion having the umbrella-shaped sealing part and a shaft portion extending perpendicularly to the valve portion are formed integrally with each other. The partition wall includes a support portion supporting the shaft portion of the valving element, multiple fluid through-holes arranged at regular intervals around the support portion, and the circular edge circularly surrounding an outer side of the multiple fluid through-holes. The circular edge constitutes a valve seat formed into a size corresponding to the outer circumferential rim of the upstream side of the sealing part.
In the conventional check valve device, the valving element having the umbrella-like shape and made of rubber is used. In this case, the valving element may repeatedly deform elastically and abruptly depending on change in pressure acting on the valving element. By the repetition of the abrupt deformations of the valving element, a stress may generate in the valving element repeatedly. Accordingly, durability of the valving element may decrease.